New particle accelerator smaller than a grain of rice

Accelerator on a chip!
Researchers have used a laser to accelerate electrons at a rate 10 times higher than conventional technology in a glass chip smaller than a grain of rice.
The advance could dramatically shrink particle accelerators for science and medicine, researchers said.
"We still have a number of challenges before this technology becomes practical for real-world use, but eventually it would substantially reduce the size and cost of future high-energy particle colliders for exploring the world of fundamental particles and forces," said Joel England, from US Department of Energy's SLAC National Accelerator Laboratory and Stanford University.
"It could also help enable compact accelerators and X-ray devices for security scanning, medical therapy and imaging, and research in biology and materials science," said England, who led the experiments.

Because it employs commercial lasers and low-cost, mass-production techniques, the researchers believe it will set the stage for new generations of "tabletop" accelerators.

The new "accelerator on a chip" could match the accelerating power of SLAC's 3.2km long linear accelerator in just 100 feet, and deliver a million more electron pulses per second.
The initial demonstration achieved an acceleration gradient, or amount of energy gained per length of the accelerator, of 300 million electronvolts per metre. That's roughly 10 times the acceleration provided by the current SLAC linear accelerator.
"Our ultimate goal for this structure is one billion electronvolts per metre, and we're already one-third of the way in our first experiment," said physics Professor Robert Byer, the principal investigator for this research.

Today's accelerators use microwaves to boost the energy of electrons. The new technique uses ultrafast lasers to drive the accelerator.
Particles are generally accelerated in two stages. First they are boosted to nearly the speed of light. Then any additional acceleration increases their energy, but not their speed; this is the challenging part.
In the accelerator-on-a-chip experiments, electrons are first accelerated to near light-speed in a conventional accelerator.
Byer said laser accelerators could drive compact X-ray free-electron lasers, comparable to SLAC's Linac Coherent Light Source, that are all-purpose tools for a wide range of research.
Another possible application is small, portable X-ray sources to improve medical care for people injured in combat, as well as to provide more affordable medical imaging for hospitals and laboratories.

The study was published in the journal Nature.